Method for detecting edible oil

Abstract

The application relates to a detection method, and discloses a method for detecting edible oil, which comprises the following steps: S1, pretreating a to-be-detected oil sample, then mixing the oil sample with an extractant I to perform extraction treatment I, so as to obtain an extraction liquid containing glycidol and an oil liquid containing glycidyl ester; S2, performing ring-opening reaction, hydrolysis reaction and purification treatment on the extraction liquid containing glycidol, so as to obtain an extraction liquid purification product; detecting the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the extraction liquid purification product, and converting the content of glycidol in the to-be-detected oil sample; performing ring-opening reaction, hydrolysis reaction and purification treatment on the oil liquid containing glycidyl ester, so as to obtain an oil liquid purification product; and detecting the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the oil liquid purification product, and converting the content of glycidyl ester in the to-be-detected oil sample. The method can accurately detect the contents of glycidol and glycidyl ester in the edible oil respectively, and can effectively improve the detection precision.

Description

TECHNICAL FIELD

[0001] The present application relates to a detection method, in particular to a method for detecting edible oil. BACKGROUND

[0002] Glycidyl esters (GEs) are esterification products of glycidol (Gly) and fatty acids, as a kind of terminal epoxy ester, which are mainly used for studying the terminal epoxidation function of esters. GEs mainly exist in refined edible oils, and the substance itself has toxic side effects. After being taken by human body, 3-chloro-1,2-propanediol ester (3-MCPD ester) which is a metabolite carcinogen can be produced in the human body. The 3-chloro-1,2-propanediol (3-MCPD) hydrolyzed from the 3-MCPD ester is a highly carcinogenic pollutant, which can exist in the kidney, reproductive system and DNA genetic system.

[0003] Since the food safety problem of GEs is discovered for a short time, the detection method for GEs is not very mature. At present, the main detection methods are direct determination method and indirect determination method. The direct determination method uses liquid chromatography-mass spectrometry (LC-MS) to quantitatively determine one or several different GEs. Because the types of GEs are more and the standard products are not easy to obtain, the popularization of the method is affected. The indirect determination method uses gas chromatography-mass spectrometry (GC-MS) to hydrolyze GEs into Gly through ester exchange reaction. Gly is converted into 3-MCPD under specific conditions. The content of Gly in the sample is calculated by difference method, and the content of Gly is used to characterize the content of GEs. In the detection process, researchers have always ignored a problem, that is, there are two kinds of conversion products of GEs. Although the conversion amount of one of them is relatively small, it will also affect the detection precision of GEs in edible oil. Moreover, the method in the prior art is mainly used for detecting the total amount of GEs and Gly, and cannot accurately measure the content of GEs and Gly in edible oil respectively. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a detection method for edible oil, which can accurately detect the content of glycidol and glycidyl ester in edible oil respectively, and can effectively improve the detection precision.

[0005] In order to solve the above technical problems, the present application provides a detection method for edible oil, comprising the following steps:

[0006] S1, pretreating the oil sample to be detected, and then mixing with an extractant I for extraction treatment I to obtain an extraction liquid containing glycidol and an oil liquid containing glycidyl ester;

[0007] S2, performing ring-opening reaction, hydrolysis reaction and purification treatment on the glycidol-containing extraction liquid to obtain an extraction liquid purification product, detecting the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the extraction liquid purification product, and converting to obtain the content of glycidol in the oil sample to be tested;

[0008] performing ring-opening reaction, hydrolysis reaction and purification treatment on the glycidol ester-containing oil liquid to obtain an oil liquid purification product, detecting the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the oil liquid purification product, and converting to obtain the content of glycidol ester in the oil sample to be tested.

[0009] Preferably, in step S1, the pretreatment comprises: mixing the oil sample to be tested with an internal standard; wherein the internal standard is a mixed solution containing deuterated 3-chloro-1,2-propanediol, deuterated 2-chloro-1,3-propanediol, deuterated 3-chloro-1,2-propanediol fatty acid ester and deuterated 2-chloro-1,2-propanediol fatty acid ester.

[0010] Further preferably, the deuterated 3-chloro-1,2-propanediol fatty acid ester is deuterated 3-chloro-1,2-propanediol palmitate monoester, and the deuterated 2-chloro-1,3-propanediol fatty acid ester is deuterated 2-chloro-1,3-propanediol stearate diester.

[0011] In step S2, the detection method is gas chromatography-mass spectrometry.

[0012] Preferably, in step S1, the extraction agent I is acetonitrile.

[0013] Further preferably, in step S1, the mass ratio of the oil sample to be tested to the acetonitrile is 1:1-2.

[0014] Preferably, step S2 comprises:

[0015] (a) taking part of the glycidol-containing extraction liquid obtained in step S1, performing ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product I, adding a water solution containing chloride ions and hydrogen ions to the hydrolysis reaction product I, uniformly mixing, then adding extraction agent II for extraction treatment II, collecting the lower aqueous phase, performing purification treatment, and detecting to convert to obtain the mass M1 of glycidol in the glycidol-containing extraction liquid;

[0016] Taking part of the glycidol-containing extract liquid obtained in step S1, ring-opening reaction and hydrolysis reaction are performed to obtain a hydrolysis reaction product II, a water solution containing sulfate ions is added into the hydrolysis reaction product II, after mixing uniformly, an extractant III is added to perform extraction treatment III, the lower aqueous phase is collected, after purification treatment, detection is performed, and the mass M2 of glycidol in the glycidol-containing extract liquid is obtained by conversion;

[0017] Taking part of the glycidol ester-containing oil liquid obtained in step S1, ring-opening reaction and hydrolysis reaction are performed to obtain a hydrolysis reaction product III, a water solution containing chloride ions and hydrogen ions is added into the hydrolysis reaction product III, after mixing uniformly, an extractant IV is added to perform extraction treatment IV, the lower aqueous phase is collected, after purification treatment, detection is performed, and the mass M3 of glycidol ester in the glycidol ester-containing oil liquid is obtained by conversion;

[0018] Taking part of the glycidol ester-containing oil liquid obtained in step S1, ring-opening reaction and hydrolysis reaction are performed to obtain a hydrolysis reaction product IV, an extractant V is added into the hydrolysis reaction product IV to perform extraction treatment V, the lower aqueous phase is collected, after purification treatment, detection is performed, and the mass M4 of glycidol ester in the glycidol ester-containing oil liquid is obtained by conversion;

[0019] (b) the content of glycidol in the oil sample to be tested is calculated according to the formula (M1-M2) / M0, wherein M0 is the mass of the oil sample to be tested,

[0020] The content of glycidol ester in the oil sample to be tested is calculated according to the formula (M3-M4) / M0.

[0021] Further preferably, in step (a), the water solution containing chloride ions and hydrogen ions is an aqueous hydrogen chloride solution, and the water solution containing sulfate ions is an aqueous sulfuric acid solution.

[0022] Preferably, the extractant II, the extractant III, the extractant IV and the extractant V are each independently selected from at least one of n-hexane, petroleum ether and n-heptane.

[0023] Preferably, in step S2, the purification treatment comprises: passing the lower aqueous phase through a diatomite chromatographic column, adding ethyl acetate to perform ethyl acetate extraction treatment, collecting the ethyl acetate layer, and performing dehydration treatment and derivatization treatment.

[0024] Further preferably, the purification treatment further comprises: concentrating the dehydration treatment product to 3-1.5 mL, and mixing it with n-hexane.

[0025] Preferably, in step S2, the ring-opening reaction comprises adding a mixed solution of methyl tert-butyl ether and ethyl acetate into the glycidol-containing extract liquid or glycidyl ester-containing oil liquid, and the volume ratio of methyl tert-butyl ether to ethyl acetate in the mixed solution is 8.5-9.5:1.

[0026] Preferably, in step S2, the hydrolysis reaction is carried out under alkaline conditions.

[0027] By the technical solution described above, the present application has the following beneficial effects:

[0028] By the extraction treatment, the oil sample to be tested is divided into the glycidol-containing extract liquid and the glycidyl ester-containing oil liquid, and then the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the glycidol-containing extract liquid and the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the glycidyl ester-containing oil liquid are detected respectively, so that the content of glycidol and the content of glycidyl ester in the edible oil can be detected simultaneously. Moreover, the content of glycidol and the content of glycidyl ester in the edible oil are obtained by converting the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol, so that the precision of detection can be effectively improved. DETAILED DESCRIPTION

[0029] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values and should be understood to include values approximately near these ranges and values within these ranges. For ranges, the endpoints are included within the ranges, and the ranges are inclusive of the single values therein. For values, the value is inclusive of the single value.

[0030] As described above, the present application provides a method for detecting edible oil, comprising the following steps:

[0031] S1, pretreating an oil sample to be tested, and then mixing the pretreated oil sample with an extractant I to perform extraction treatment I, so as to obtain a glycidol-containing extract liquid and a glycidyl ester-containing oil liquid;

[0032] S2, performing ring-opening reaction, hydrolysis reaction and purification treatment on the glycidol-containing extract liquid, so as to obtain an extract liquid purification product, detecting the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the extract liquid purification product, and converting to obtain the content of glycidol in the oil sample to be tested;

[0033] The oil liquid containing glycidyl ester is subjected to ring-opening reaction, hydrolysis reaction and purification treatment to obtain an oil liquid purification product, the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the oil liquid purification product is detected, and the content of glycidyl ester in the oil sample to be detected is converted.

[0034] Specifically, the extractant I can adopt any one of the extractants capable of distinguishing glycidol and glycidyl ester disclosed in the prior art. The ring-opening reaction and the hydrolysis reaction can be any one of the reactions capable of converting glycidol and glycidyl ester into 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol disclosed in the prior art. The total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the purification product can also be detected by any method that can be achieved. The conversion method can be determined by a person skilled in the art according to the actual detection situation.

[0035] The inventors of the present application found in the research process that, by using the above-mentioned method of the present application, the oil sample to be detected is divided into an extract liquid containing glycidol and an oil liquid containing glycidyl ester through extraction treatment, and then the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the extract liquid containing glycidol and the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the oil liquid containing glycidyl ester are detected, which can simultaneously detect the content of harmful substance glycidol and the content of glycidyl ester in edible oil. Moreover, by converting the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol to obtain the content of glycidol and the content of glycidyl ester in edible oil, the precision of detection can be effectively improved.

[0036] In order to further improve the precision of detection, preferably, in step S1, the pretreatment comprises: mixing the oil sample to be detected with an internal standard; wherein the internal standard is a mixed solution containing deuterated 3-chloro-1,2-propanediol, deuterated 2-chloro-1,3-propanediol, deuterated 3-chloro-1,2-propanediol fatty acid ester and deuterated 2-chloro-1,3-propanediol fatty acid ester; and in step S2, the detection method is gas chromatography-mass spectrometry.

[0037] The deuterated 3-chloro-1,2-propanediol fatty acid ester can be selected from any one or more deuterated 3-chloro-1,2-propanediol fatty acid esters in the prior art, the deuterated 2-chloro-1,3-propanediol fatty acid ester can be selected from any one or more deuterated 3-chloro-1,2-propanediol fatty acid esters in the prior art, and the fatty acid is preferably a C12-C20 fatty acid. In order to further improve the precision of detection, the deuterated 3-chloro-1,2-propanediol fatty acid ester is deuterated 3-chloro-1,2-propanediol palmitate monoester, and the deuterated 2-chloro-1,3-propanediol fatty acid ester is deuterated 2-chloro-1,3-propanediol stearate diester.

[0038] In order to further improve the separation effect of glycidol and glycidyl ester, preferably, in the step S1, the extractant I is acetonitrile.

[0039] The to-be-tested oil sample and the acetonitrile can be mixed in any mass ratio. In order to further improve the separation effect of glycidol and glycidyl ester and improve the detection precision, preferably, in the step S1, the mass ratio of the to-be-tested oil sample to the acetonitrile is 1:1-2.

[0040] In order to further improve the precision of detection, preferably, the step S2 comprises:

[0041] (a) taking part of the glycidol-containing extract obtained in the step S1, performing ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product I, adding an aqueous solution containing chloride ions and hydrogen ions into the hydrolysis reaction product I, uniformly mixing, then adding an extractant II to perform extraction treatment II, collecting the lower aqueous phase, performing purification treatment, then detecting and converting to obtain the mass M1 of glycidol in the glycidol-containing extract;

[0042] Taking part of the glycidol-containing extract obtained in the step S1, performing ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product II, adding an aqueous solution containing sulfate ions into the hydrolysis reaction product II, uniformly mixing, then adding an extractant III to perform extraction treatment III, collecting the lower aqueous phase, performing purification treatment, then detecting and converting to obtain the mass M2 of glycidol in the glycidol-containing extract;

[0043] Taking part of the glycidyl ester-containing oil liquid obtained in the step S1, performing ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product III, adding an aqueous solution containing chloride ions and hydrogen ions into the hydrolysis reaction product III, uniformly mixing, then adding an extractant IV to perform extraction treatment IV, collecting the lower aqueous phase, performing purification treatment, then detecting and converting to obtain the mass M3 of glycidyl ester in the glycidyl ester-containing oil liquid;

[0044] A portion of the glycidyl ester-containing oil liquid obtained in step S1 is subjected to ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product IV, and an extractant V is added to the hydrolysis reaction product IV to perform extraction treatment V, and the lower aqueous phase is collected, and after purification treatment, detection is performed, and the mass M4 of the glycidyl ester in the glycidyl ester-containing oil liquid is obtained by conversion;

[0045] (b) the content of glycidol in the oil sample to be measured is calculated according to the formula (M1-M2) / M0, wherein M0 is the mass of the oil sample to be measured,

[0046] The content of glycidyl ester in the oil sample to be measured is calculated according to the formula (M3-M4) / M0.

[0047] Specifically, the volume of the glycidol-containing extract liquid obtained by extraction in step S1 is V1 L, the volume of the extract liquid taken at a time during detection is V2 L, the volume at the last measurement is V3 L, and the total solubility of 3-chloro-1,2-propanediol and 2-chloro-1,2-propanediol detected is c1 mol / L. M1=M 缩水甘油 ·(c1)·V3·V1 / V2, wherein M 缩水甘油 is the molecular weight of glycidol.

[0048] The volume of the glycidyl ester-containing oil liquid obtained by extraction in step S1 is V4 L, the volume of the oil liquid taken at a time during detection is V5 L, the volume at the last measurement is V6 L, and the total concentration of 3-chloro-1,2-propanediol and 2-chloro-1,2-propanediol detected is c2 mol / L. M3=M 缩水甘油酯 ·(c2-c0)V6·V4 / V5, wherein M 缩水甘油酯 is the molecular weight of glycidyl ester.

[0049] In order to further improve the accuracy of detection, preferably, the amount of glycidol-containing extract liquid taken twice is consistent, and the volume of the glycidol final measurement solution is also consistent; the amount of glycidyl ester-containing oil liquid taken twice is consistent, and the volume of the glycidyl ester final measurement solution is also consistent. Such settings can reduce the influence of glycidyl ester and glycidol in the blank sample on the test results, thereby improving the accuracy of detection.

[0050] In the method provided by the above specific embodiment, through detection of M2 and M4, 3-MCPD ester and 2-MCPD ester originally contained in the edible oil can be removed, so that the precision of the content of glycidol and the content of glycidyl ester in the edible oil obtained by conversion is higher.

[0051] The water solution containing chloride ion and hydrogen ion can be any water solution containing chloride ion and hydrogen ion, such as sodium chloride solution acidified by sulfuric acid or nitric acid. The water solution containing sulfate ion can be any water solution containing sulfate ion. In order to further improve the precision of detection, preferably, in step (a), the water solution containing chloride ion and hydrogen ion is aqueous hydrogen chloride solution, and the water solution containing sulfate ion is aqueous sulfuric acid solution. The use of aqueous hydrogen chloride solution and aqueous sulfuric acid solution can improve the detection precision.

[0052] The concentration of the aqueous hydrogen chloride solution and the aqueous sulfuric acid solution can be any concentration, and the addition amount of the aqueous hydrogen chloride solution and the addition amount of the aqueous sulfuric acid solution can be determined by those skilled in the art according to the concentration of the aqueous hydrogen chloride solution, the concentration of the aqueous sulfuric acid solution, and the amount of the hydrolysis product.

[0053] The extractant II, the extractant III, the extractant IV, and the extractant V can be any extractant capable of extracting 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the prior art. In order to further improve the precision of detection, preferably, the extractant II, the extractant III, the extractant IV, and the extractant V are each independently selected from at least one of n-hexane, petroleum ether, and n-heptane. That is, the extractant II, the extractant III, the extractant IV, and the extractant V can each be at least one of n-hexane, petroleum ether, and n-heptane, and the extractant II, the extractant III, the extractant IV, and the extractant V can be the same or different. Preferably, n-hexane is used as the extractant, which can improve the extraction efficiency. The extractant II, the extractant III, the extractant IV, and the extractant V can be mixed with the solution to be extracted in any ratio. In order to ensure the extraction effect and reduce the extraction cost, the volume ratio of the n-hexane to the solution to be extracted is 0.5-1:1, and in the embodiments of the present application, the volume ratio of the n-hexane to the solution to be extracted is 0.5:1.

[0054] In order to further improve the precision of detection, preferably, in step S2, the purification treatment includes passing the lower aqueous phase through a silica gel column, adding ethyl acetate for ethyl acetate extraction treatment, collecting the ethyl acetate layer, and performing dehydration treatment and derivatization treatment.

[0055] In order to improve the derivatization effect and thus improve the detection precision, preferably, the derivatization uses heptafluorobutyrylimidazole (HFBI). The amount of heptafluorobutyrylimidazole used, the derivatization time, and the derivatization temperature can be determined by those skilled in the art according to the actual situation. The cutoff of derivatization can also use the technical means commonly used in the art, such as adding sodium chloride solution.

[0056] In order to further improve the detection precision, preferably, the dehydration is performed by using sodium sulfate. The dehydration by using sodium sulfate can improve the dehydration effect and facilitate the removal of the dehydration agent.

[0057] In order to further improve the detection precision, preferably, the purification process further comprises: concentrating the dehydration product to 0.3-1.5 mL and mixing it with n-hexane.

[0058] In order to further improve the detection precision, preferably, in step S2, the ring-opening reaction comprises: adding a mixed solution of methyl tert-butyl ether and ethyl acetate into the glycidol-containing extraction liquid or glycidyl ester-containing oil liquid, the volume ratio of methyl tert-butyl ether and ethyl acetate in the mixed solution being 8.5-9.5:1. By using the mixed solution of methyl tert-butyl ether and ethyl acetate with a volume ratio of 8.5-9.5:1, the detection precision of glycidol and glycidyl ester can be effectively improved.

[0059] Specifically, the time and temperature of the ring-opening reaction can be determined by those skilled in the art according to actual conditions.

[0060] In order to further improve the detection precision, preferably, in step S2, the hydrolysis reaction is performed under alkaline conditions. The hydrolysis efficiency can be improved, thereby improving the detection precision of glycidol and glycidyl ester.

[0061] Preferably, before the hydrolysis process, the pH of the solution is controlled to be about 1. The alkaline conditions are provided by sodium methoxide or other substances that can provide hydroxyl ions in aqueous solution. Preferably, it is sodium C1-C4 alcoholate. More preferably, it is sodium methoxide. The hydrolysis time and hydrolysis temperature can be determined according to actual conditions.

[0062] In the present application, the uniform mixing can be performed by any method that can be achieved, preferably vortex centrifugal mixing, which can further improve the measurement accuracy. The rotation speed of vortex centrifugal mixing is 2000-10000 rpm, and the centrifugal time is 2-10 min.

[0063] As a relatively preferred embodiment of the present application, a method for detecting edible oil is provided, comprising the following steps:

[0064] S1, mixing the oil sample to be detected with an internal standard, and then mixing with acetonitrile (the volume ratio of the oil sample to be detected to acetonitrile is 1:1-2) for extraction treatment I to obtain a glycidol-containing extraction liquid and a glycidyl ester-containing oil liquid;

[0065] The internal standard is a mixed solution containing deuterated 3-chloro-1,2-propanediol, deuterated 2-chloro-1,3-propanediol, deuterated 3-chloro-1,2-propanediol fatty acid ester and deuterated 2-chloro-1,3-propanediol fatty acid ester;

[0066] S2, take part of the glycidol-containing extract liquid obtained in step S1, add a mixed solution of methyl tert-butyl ether and ethyl acetate (the volume ratio of methyl tert-butyl ether and ethyl acetate is 8.5-9.5:1) to the glycidol-containing extract liquid, and perform hydrolysis reaction under alkaline conditions to obtain a hydrolysis reaction product I, add an aqueous hydrogen chloride solution to the hydrolysis reaction product I, mix uniformly, and then add an extractant II to perform extraction treatment II, collect the lower aqueous phase, pass the lower aqueous phase through a diatomite chromatographic column, add ethyl acetate to perform ethyl acetate extraction treatment, collect the ethyl acetate layer, dehydrate, concentrate to 0.3-1.5 mL, add n-hexane for dilution and mixing, derivatize, detect by gas chromatography-mass spectrometry, and convert to obtain the mass M1 of glycidol in the glycidol-containing extract liquid;

[0067] S2, take part of the glycidol-containing extract liquid obtained in step S1, add a mixed solution of methyl tert-butyl ether and ethyl acetate (the volume ratio of methyl tert-butyl ether and ethyl acetate is 8.5-9.5:1) to the glycidol-containing extract liquid, and perform hydrolysis reaction under alkaline conditions to obtain a hydrolysis reaction product I, add an aqueous hydrogen chloride solution to the hydrolysis reaction product I, mix uniformly, and then add an extractant II to perform extraction treatment II, collect the lower aqueous phase, pass the lower aqueous phase through a diatomite chromatographic column, add ethyl acetate to perform ethyl acetate extraction treatment, collect the ethyl acetate layer, dehydrate, concentrate to 0.3-1.5 mL, add n-hexane for dilution and mixing, derivatize, detect by gas chromatography-mass spectrometry, and convert to obtain the mass M1 of glycidol in the glycidol-containing extract liquid;

[0068] S2, take part of the glycidol-containing extract liquid obtained in step S1, add a mixed solution of methyl tert-butyl ether and ethyl acetate (the volume ratio of methyl tert-butyl ether and ethyl acetate is 8.5-9.5:1) to the glycidol-containing extract liquid, and perform hydrolysis reaction under alkaline conditions to obtain a hydrolysis reaction product I, add an aqueous hydrogen chloride solution to the hydrolysis reaction product I, mix uniformly, and then add an extractant II to perform extraction treatment II, collect the lower aqueous phase, pass the lower aqueous phase through a diatomite chromatographic column, add ethyl acetate to perform ethyl acetate extraction treatment, collect the ethyl acetate layer, dehydrate, concentrate to 0.3-1.5 mL, add n-hexane for dilution and mixing, derivatize, detect by gas chromatography-mass spectrometry, and convert to obtain the mass M1 of glycidol in the glycidol-containing extract liquid;

[0069] Part of the glycidyl ester-containing oil liquid obtained in step S1 is taken, a mixed solution of methyl tert-butyl ether and ethyl acetate (volume ratio of methyl tert-butyl ether to ethyl acetate is 8.5-9.5:1) is added to the glycidyl ester-containing oil liquid, a hydrolysis reaction is carried out under alkaline conditions to obtain a hydrolysis reaction product IV, an extractant V is added to the hydrolysis reaction product IV for extraction treatment V, the lower aqueous phase is collected, the lower aqueous phase is passed through a diatomite chromatographic column, ethyl acetate is added for ethyl acetate extraction treatment, the ethyl acetate layer is collected, dehydrated, concentrated to 0.3-1.5 mL, diluted by mixing with n-hexane, derivatized, detected by gas chromatography-mass spectrometry, and the mass M4 of the glycidyl ester in the glycidyl ester-containing oil liquid is calculated.

[0070] S3, the content of glycidol in the oil sample to be tested is calculated according to the formula (M1-M2) / M0, wherein M0 is the mass of the oil sample to be tested.

[0071] The content of glycidyl ester in the oil sample to be tested is calculated according to the formula (M3-M4) / M0.

[0072] The application will be described in detail below by way of examples.

[0073] Concentrated sulfuric acid, concentrated hydrochloric acid, anhydrous sodium sulfate, sodium methoxide (content ≥95%, solid powder), ethyl acetate (chromatographic pure), methyl tert-butyl ether (chromatographic pure), heptafluorobutyrylimidazole (chromatographic pure), n-hexane (chromatographic pure), methanol (chromatographic pure), acetonitrile (chromatographic pure), D5-3-chloro-1,2-propanediol (purity ≥98%), D5-2-chloro-1,3-propanediol (purity ≥98%), D5-3-chloro-1,2-propanediol palmitate (purity 98.6%), and D5-2-chloro-1,3-propanediol stearate (purity 98.5%) were all purchased from National Pharmaceutical Group.

[0074] Diatomite ExtrelutTM20 was used.

[0075] The gas chromatograph was purchased from Agilent Company, USA, and the product model was 7890B; the mass spectrometer was purchased from Agilent Company, USA, and the product model was 5977B.

[0076] Gas chromatography conditions

[0077] Chromatographic column: DB-5MS (30 m x 0.25 mm x 0.25 μm) quartz capillary column.

[0078] Injection port temperature: 250°C.

[0079] Programmed temperature rise: 50°C for 1 min, 2°C / min to 90°C, 40°C / min to 270°C, and hold for 5 min.

[0080] Carrier gas: high purity helium, purity ≥ 99.999%.

[0081] Flow rate: 1.0 mL / min.

[0082] Injection mode: splitless injection.

[0083] Injection volume: 1.0 μL.

[0084] Mass spectrometry reference conditions

[0085] Ion mode: EI.

[0086] Electron impact source: 70 eV.

[0087] Ion source temperature: 230°C.

[0088] GC-MS interface temperature: 280°C.

[0089] Monitoring ions and quantitative ions are as shown in Table 1 (m / z):

[0090] Table 1

[0091] target quantifier ion qualifier ion d5-3-mcpd derivative 257 278、297、296 3-mcpd derivative 253 275、289、291 d5-2-mcpd derivative 257 278、297、296 2-mcpd derivative 253 275、289、291

[0092] The internal standard is a mixed solution containing D5-3-chloro-1,2-propanediol, D5-2-chloro-1,3-propanediol, D5-3-chloro-1,2-propanediol palmitate and D5-2-chloro-1,3-propanediol stearate. In the internal standard provided in the following examples, the solubility of D5-3-chloro-1,2-propanediol is 10 mg / L, the solubility of D5-2-chloro-1,3-propanediol is 10 mg / L, the concentration of D5-3-chloro-1,2-propanediol palmitate is 10 mg / L, and the concentration of D5-2-chloro-1,3-propanediol stearate is 10 mg / L.

[0093] Example 1

[0094] S1, 0.5 g of the oil sample to be tested is mixed with 0.05 mL of the internal standard, and then mixed with 0.75 g of acetonitrile for extraction treatment I to obtain an extract containing glycidol and an oil liquid containing glycidyl ester;

[0095] S2, take 0.1 mL of the glycidol-containing extract obtained in step S1, add 0.5 mL of a mixed solution of methyl tert-butyl ether and ethyl acetate (volume ratio of methyl tert-butyl ether to ethyl acetate is 9:1) to the glycidol-containing extract, add 1 mL of a sodium methoxide-methanol solution (0.5 mol / L), hydrolyze to obtain a hydrolysis reaction product I, add 1 mL of an aqueous hydrogen chloride solution (1.2 mol / L) to the hydrolysis reaction product I, mix uniformly, then add 2 mL of n-hexane for extraction treatment II, collect the lower aqueous phase, pass the lower aqueous phase through a diatomite chromatographic column, add 20 mL of ethyl acetate for extraction treatment, collect the ethyl acetate layer, dehydrate, concentrate to 0.5 mL, mix uniformly with 2 mL of n-hexane, then add 0.1 mL of heptafluorobutyrylimidazole, derive at 70°C for 30 min, detect by gas chromatography-mass spectrometry, and calculate the mass M1 of glycidol in the glycidol-containing extract;

[0096] S2, take 0.1 mL of the glycidol-containing extract obtained in step S1, add 0.5 mL of a mixed solution of methyl tert-butyl ether and ethyl acetate (volume ratio of methyl tert-butyl ether to ethyl acetate is 9:1) to the glycidol-containing extract, add 1 mL of a sodium methoxide-methanol solution (0.5 mol / L), hydrolyze to obtain a hydrolysis reaction product I, add 1 mL of an aqueous hydrogen chloride solution (1.2 mol / L) to the hydrolysis reaction product I, mix uniformly, then add 2 mL of n-hexane for extraction treatment II, collect the lower aqueous phase, pass the lower aqueous phase through a diatomite chromatographic column, add 20 mL of ethyl acetate for extraction treatment, collect the ethyl acetate layer, dehydrate, concentrate to 0.5 mL, mix uniformly with 2 mL of n-hexane, then add 0.1 mL of heptafluorobutyrylimidazole, derive at 70°C for 30 min, detect by gas chromatography-mass spectrometry, and calculate the mass M1 of glycidol in the glycidol-containing extract;

[0097] S2, take 0.1 mL of the glycidol-containing extract obtained in step S1, add 0.5 mL of a mixed solution of methyl tert-butyl ether and ethyl acetate (volume ratio of methyl tert-butyl ether to ethyl acetate is 9:1) to the glycidol-containing extract, add 1 mL of a sodium methoxide-methanol solution (0.5 mol / L), hydrolyze to obtain a hydrolysis reaction product I, add 1 mL of an aqueous hydrogen chloride solution (1.2 mol / L) to the hydrolysis reaction product I, mix uniformly, then add 2 mL of n-hexane for extraction treatment II, collect the lower aqueous phase, pass the lower aqueous phase through a diatomite chromatographic column, add 20 mL of ethyl acetate for extraction treatment, collect the ethyl acetate layer, dehydrate, concentrate to 0.5 mL, mix uniformly with 2 mL of n-hexane, then add 0.1 mL of heptafluorobutyrylimidazole, derive at 70°C for 30 min, detect by gas chromatography-mass spectrometry, and calculate the mass M1 of glycidol in the glycidol-containing extract;

[0098] Take 0.1 mL of the glycidyl ester-containing oil liquid obtained in step S1, add 0.5 mL of a mixed solution of methyl tert-butyl ether and ethyl acetate (volume ratio of methyl tert-butyl ether to ethyl acetate is 9:1) to the glycidyl ester-containing oil liquid, add 1 mL of sodium methoxide-methanol solution (0.5 mol / L), hydrolyze to obtain a hydrolysis reaction product IV, add 2 mL of n-hexane to the hydrolysis reaction product IV for extraction treatment V, collect the lower aqueous phase, pass the lower aqueous phase through a silica gel chromatographic column, add 20 mL of ethyl acetate for extraction treatment, collect the ethyl acetate layer, dehydrate, concentrate to 0.5 mL, mix uniformly with 2 mL of n-hexane, then add 0.1 mL of heptafluorobutyrylimidazole at 70°C for 30 min, and detect by gas chromatography-mass spectrometry to obtain the mass M4 of glycidyl ester in the glycidyl ester-containing oil liquid by conversion;

[0099] S3, calculate the content of glycidol in the oil sample to be tested according to the formula (M1-M2) / 0.5g,

[0100] According to the formula (M3-M4) / 0.5g, the content of glycidyl ester in the oil sample to be tested is calculated.

[0101] Take eighteen blank edible oil matrices, divide them into three groups (groups A, B and C) on average, add 0.05 mg / kg of glycidyl ester and 0.05 mg / kg of glycidol to group A, add 0.1 mg / kg of glycidyl ester and 0.1 mg / kg of glycidol to group B, and add 0.5 mg / kg of glycidyl ester and 0.5 mg / kg of glycidol to group C to obtain oil samples to be tested, process them according to the above method, analyze them on the instrument, and bring in the standard curve to calculate the standard addition recovery rate and the relative standard deviation (RSD%) of glycidol and its ester, respectively. The results are shown in Table 2.

[0102] Table 2

[0103]

[0104] Example 2

[0105] On the basis of Example 1, the following changes are made: in step S2, the volume ratio of methyl tert-butyl ether to ethyl acetate is changed to 8:1. The measurement results are shown in Table 3.

[0106] Table 3

[0107]

[0108] Example 3

[0109] The following changes were made on the basis of Example 1: in step S2, the dehydration product was directly subjected to derivatization treatment, and the steps of concentration and mixing with n-hexane were reduced. The measurement results are shown in Table 4.

[0110] Table 4

[0111]

[0112] Comparative Example

[0113] S1, 0.5 g of the oil sample to be tested was mixed with 0.05 mL of an internal standard (deuterated 3-chloro-1,2-propanediol, 10 mg / L in solubility), to obtain a mixed oil liquid;

[0114] S2, 0.1 mL of the mixed oil liquid obtained in step S1 was taken, 0.5 mL of a mixed solution of methyl tert-butyl ether and ethyl acetate (volume ratio of methyl tert-butyl ether to ethyl acetate was 8:1) was added to the mixed oil liquid, 1 mL of a sodium methoxide-methanol solution (0.5 mol / L) was added, hydrolysis was performed, to obtain a hydrolysis reaction product I, 1 mL of an aqueous hydrogen chloride solution (1.2 mol / L) was added to the hydrolysis reaction product I, after uniform mixing, 2 mL of n-hexane was added for extraction treatment II, the lower aqueous phase was collected, the lower aqueous phase was passed through a diatomite chromatographic column, 20 mL of ethyl acetate was added for extraction treatment, the ethyl acetate layer was collected, dehydration was performed, 0.1 mL of heptafluorobutyrylimidazole was added for derivatization at 70°C for 30 min, gas chromatography-mass spectrometry detection was performed, and the mass M1 of glycidol in the glycidol-containing extraction liquid was calculated;

[0115] 0.1 mL of the mixed oil liquid obtained in step S1 was taken, 0.5 mL of a mixed solution of methyl tert-butyl ether and ethyl acetate (volume ratio of methyl tert-butyl ether to ethyl acetate was 8:1) was added to the mixed oil liquid, 1 mL of a sodium methoxide-methanol solution (0.5 mol / L) was added, hydrolysis was performed, to obtain a hydrolysis reaction product II, 1 mL of an aqueous sulfuric acid solution (0.7 mol / L) was added to the hydrolysis reaction product II, after uniform mixing, 2 mL of n-hexane was added for extraction treatment III, the lower aqueous phase was collected, the lower aqueous phase was passed through a diatomite chromatographic column, 20 mL of ethyl acetate was added for extraction treatment, the ethyl acetate layer was collected, dehydration was performed, 0.1 mL of heptafluorobutyrylimidazole was added for derivatization at 70°C for 30 min, gas chromatography-mass spectrometry detection was performed, and the mass M2 of glycidol in the glycidol-containing extraction liquid was calculated;

[0116] S3, the content of glycidyl ester in the oil sample to be tested was calculated according to the formula (M1-M2) / 5 g.

[0117] Take eighteen blank edible oil matrix, divided into three groups (group A, group B and group C) on average, group A is added 0.05mg / kg glycidyl ester and 0.05mg / kg glycidol, group B is added 0.1mg / kg glycidyl ester and 0.1mg / kg glycidol, group C is added 0.5mg / kg glycidyl ester and 0.5mg / kg glycidol, get the oil sample to be tested, according to the above method, on machine analysis, into the standard curve, respectively calculate the glycidol and its ester standard recovery and relative standard deviation (RSD%), the results are shown in table 5.

[0118] Table 5

[0119]

[0120] The data of comparative examples and examples show that by using the above method of the application, the oil sample to be tested is divided into an extract containing glycidol and an oil liquid containing glycidyl ester by extraction treatment, and then the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the extract containing glycidol and the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol in the oil liquid containing glycidyl ester are detected respectively, so that the content of harmful substance glycidol and the content of glycidyl ester in edible oil can be detected simultaneously. Moreover, the content of glycidol and the content of glycidyl ester in edible oil are obtained by converting the total content of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol, so that the precision of detection can be effectively improved.

[0121] The above describes the preferred embodiments of the application in detail, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and fall within the protection scope of the application.

Claims

1. A method of detecting edible oil, characterized by, The method comprises the following steps: S1, pretreating the oil sample to be tested, and then mixing the pretreated oil sample with an extractant I to perform extraction treatment I, so as to obtain an extractant containing glycidol and an oil liquid containing glycidyl ester; the extractant I is acetonitrile; S2, (a) taking part of the extractant containing glycidol obtained in step S1, performing ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product I, adding hydrogen chloride aqueous solution into the hydrolysis reaction product I, mixing uniformly, then adding an extractant II to perform extraction treatment II, collecting the lower aqueous phase, performing purification treatment, then detecting the total content of derivatives of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol by gas chromatography-mass spectrometry, and calculating the mass M1 of glycidol in the extractant containing glycidol; taking part of the extractant containing glycidol obtained in step S1, performing ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product II, adding sulfuric acid aqueous solution into the hydrolysis reaction product II, mixing uniformly, then adding an extractant III to perform extraction treatment III, collecting the lower aqueous phase, performing purification treatment, then detecting the total content of derivatives of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol by gas chromatography-mass spectrometry, and calculating the mass M2 of glycidol in the extractant containing glycidol; taking part of the oil liquid containing glycidyl ester obtained in step S1, performing ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product III, adding hydrogen chloride aqueous solution into the hydrolysis reaction product III, mixing uniformly, then adding an extractant IV to perform extraction treatment IV, collecting the lower aqueous phase, performing purification treatment, then detecting the total content of derivatives of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol by gas chromatography-mass spectrometry, and calculating the mass M3 of glycidyl ester in the oil liquid containing glycidyl ester; taking part of the oil liquid containing glycidyl ester obtained in step S1, performing ring-opening reaction and hydrolysis reaction to obtain a hydrolysis reaction product IV, adding an extractant V into the hydrolysis reaction product IV to perform extraction treatment V, collecting the lower aqueous phase, performing purification treatment, then detecting the total content of derivatives of 3-chloro-1,2-propanediol and 2-chloro-1,3-propanediol by gas chromatography-mass spectrometry, and calculating the mass M4 of glycidyl ester in the oil liquid containing glycidyl ester; the extractant II, the extractant III, the extractant IV and the extractant V are each selected from at least one of n-hexane, petroleum ether and n-heptane; the purification treatment comprises: passing the lower aqueous phase through a diatomite chromatographic column, adding ethyl acetate to perform ethyl acetate extraction treatment, collecting the ethyl acetate layer, performing dehydration treatment, and then performing derivatization treatment by using heptafluorobutyrylimidazole; (b) according to formula (M1-M2) / M0, the content of glycidol in the oil sample to be tested is calculated, according to formula (M3-M4) / M0, the content of glycidyl ester in the oil sample to be tested is calculated.

2. The method of detecting edible oil according to claim 1, characterized in that, In step S1, the pretreatment comprises: mixing the oil sample to be tested with an internal standard. The internal standard is a mixed solution containing deuterated 3-chloro-1,2-propanediol, deuterated 2-chloro-1,3-propanediol, deuterated 3-chloro-1,2-propanediol fatty acid ester and deuterated 2-chloro-1,3-propanediol fatty acid ester.

3. The method of detecting edible oil according to claim 2, wherein, In the step S1, the mass ratio of the oil sample to be tested to the acetonitrile is 1:1-2.

4. The method of detecting edible oil according to any one of claims 1 to 3, characterized in that, In the step S2, the purification treatment further includes: concentrating the dehydration treatment product to 0.3-1.5 mL and mixing it with n-hexane.

5. The method of detecting edible oil according to any one of claims 1 to 3, characterized in that, In the step S2, the ring-opening reaction includes: adding a mixed solution of methyl tert-butyl ether and ethyl acetate to the glycidol-containing extraction solution or the glycidyl ester-containing oil solution, and the volume ratio of methyl tert-butyl ether to ethyl acetate in the mixed solution is 8.5-9.5:

1.

6. The method of detecting edible oil according to any one of claims 1 to 3, characterized in that, In the step S2, the hydrolysis reaction is carried out under alkaline conditions. In the step S2, the hydrolysis reaction is carried out under alkaline conditions.

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